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ZeitschriftenaufsatzAccess status: Open Access ,
Ancestral chromosome-level assemblies reveal posthybridization genome evolution in the New Mexico whiptail lizard (Aspidoscelis neomexicanus)
(2025) Ho, David V.; Odell, Aaron; Tormey, Duncan; Deimler, Nathaniel; Patterson, Valentine; Tsuchiya, Dai; Klabacka, Randy L.; Schnittker, Robert R.; Baumann, Diana P.; Neaves, William B.; Barley, Anthony J.; Baumann, Peter
Unisexual species of whiptail lizards in the genus Aspidoscelis arose by interspecific hybridization. They reproduce clonally through parthenogenesis and are thought to maintain the fixed heterozygosity that resulted from their hybrid origin by avoiding recombination between homeologous chromosomes. In the absence of chromosome-level assemblies for the sexual progenitor species, questions relating to the long-term consequences of clonal reproduction have remained largely unanswered. Here, we present chromosome-level genome assemblies for A. marmoratus and A. arizonae, the parental species of the unisexual A. neomexicanus. Using these references, we have analyzed whole-genome sequencing data from both wild and laboratory-reared A. neomexicanus individuals as well as newly generated F1 hybrids. Our analysis identified population-specific losses of heterozygosity affecting multiple syntenic chromosome pairs, demonstrating that homeologous chromosome pairing and recombination must occur at a low frequency and contribute to genome erosion in these unisexual lineages. The loss of heterozygosity patterns we observed further suggest that the genomes of unisexual lineages diverge over time more quickly than anticipated based on mutation accumulation alone. Our results establish genomic resources for Aspidoscelis and provide new insights into how genome structure can evolve in the absence of sexual reproduction.
ZeitschriftenaufsatzAccess status: Open Access ,
Does Ramadan fasting influence time-motion metrics and psychophysiological responses in soccer players during small-sided games performed in fed and fasted states?
(2026) Kerkeni, Mohamed; Chamari, Karim; Kerkeni, Manel; Boukhris, Omar; Ammar, Achraf; Pyne, David B.; Husain, Waqar; Chtourou, Hamdi; Aziz, Abdul Rashid; Jahrami, Haitham; Trabelsi, Khaled
We explored how Ramadan fasting (RF) influences GPS-derived time-motion metrics and psychophysiological responses in soccer players during small-sided games (SSG). Twelve semi-professional male players (mean age 21.1 ± 0.7 y; estimated V ̇ O2max 54.5 ± 2.2 mL/min/kg) participated in four experimental SSG sessions in a within-subject, counterbalanced design. These sessions were scheduled at 15:00 and 21:00 before Ramadan, in a fed state (i.e., BR15fed and BR21fed), and during the fourth week of Ramadan at 15:00 in a fasted state (DR15fasted) and at 21:00 in a fed state (DR21fed). Sleep patterns, dietary intake, and insomnia symptoms were evaluated during the week preceding and final week-of-Ramadan. Participants’ Hooper index (wellness) and daytime sleepiness and mood measures were assessed before each session. Time-motion metrics using GPS and exercise heart rate (HR) were assessed during all sessions, and ratings of perceived exertion (RPE) were collected after each session. Except for a higher number of decelerations in DR21fed session (p < 0.001), RF had no significant effect on other time-motion metrics. Absolute and relative exercise HR were higher at BR15fed than at BR21fed and at DR15fasted. RPE, Hooper index scores, and perceptual stress and muscle soreness components were higher at DR15fasted compared to BR15fed. Additionally, RF was associated with decreased sleep duration (by ~45 minutes) and increased insomnia symptoms and daytime sleepiness, while mood states and dietary intake were unchanged. RF induced physiological and perceptual changes in response to exercise, particularly in the fasted state. However, SSG performance metrics remained stable, suggesting fasted athletes can maintain short-duration SSG performance regardless of fasting status.
ZeitschriftenaufsatzAccess status: Open Access ,
Luck can explain the positive link between fecundity and longevity : the Matthew effect in social insects and beyond
(2025) Zug, Roman; Foitzik, Susanne; Kokko, Hanna
The universality of the trade-off between fecundity and longevity in life-history theory is sometimes contested. Social insects present the arguably strongest challenge, as (i) queens not only monopolize reproduction, but also live much longer than workers, and (ii) within a caste, those individuals that lay more eggs are also observed to live longer. Positive fecundity–longevity relationships can appear in observational data even though an underlying trade-off exists, as individual variation in resource acquisition (e.g., variation in habitat quality) can mask the trade-off. Here, we demonstrate theoretically that the fecundity–longevity trade-off in social insects can be easily masked even without differences in individual quality. Demographic stochasticity, caused by variable worker lifespans, leads to self-reinforcing dynamics (equivalent to the well-known Matthew effect), where “lucky” colonies exhibit healthy growth and long-lived, productive queens, while “unlucky” colonies show the opposite combination of traits. Allocation variation between individual queens, if present, can unmask the trade-off in principle, but the trade-off remains commonly concealed not only when measuring fecundity as a cumulative total (a strongly confounded measure as longer-lived queens have more time to produce eggs), but also when measuring fecundity as a rate. Our results help align superorganismal fitness components with general life-history principles, and highlight the necessity of experimental manipulations when making statements regarding trade-offs or the lack thereof.